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Questions tagged [polymers]

For questions about synthetic or natural polymers, their chemical or physical properties, and their synthesis, etc.

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28 votes
2 answers
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Ripping apart plastic: is this a chemical or physical change?

I was holding a piece of plastic earlier, and I ripped it in half. This caused me to start to think about what was happening at the atomic level. If the plastic is being ripped, clearly bonds are ...
ringo's user avatar
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42 votes
7 answers
44k views

Is there any chemical that can destroy PTFE or Teflon?

Polytetrafluoroethylene was discovered by accident. It now is an important material in the industry mainly because of its extremely high bonding energy, which prevents corrosion, halts reaction, and ...
HyperLuminal's user avatar
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11 votes
2 answers
9k views

What is the difference between polyethene and polyethane?

The monomer in polyethene seems to drop the $\ce{C=C}$ bond and end up with a $\ce{C-C}$ bond. The polymer chain then looks like $\ce{[CH2-CH2]_{n}}$. If I were to look at that polymer chain I would ...
sion's user avatar
  • 221
7 votes
1 answer
7k views

Why are regular plastic bags not smell-proof?

Due to the wide use of plastic bags as containers for almost everything in everyday life, I naturally use them to wrap and hold dirty diapers as a temporary stop before getting to throw them in the ...
Don_S's user avatar
  • 1,410
6 votes
1 answer
2k views

Why does plastic tear easier when you pull it quickly?

If you've ever taken the plastic from a plastic bag and pulled on it, you might know what I mean. If you pull quickly, the plastic tears relatively easily, but if you pull it slowly, it gets stretched ...
ringo's user avatar
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4 votes
1 answer
1k views

Is so called "Polymerized LiNb (Lithium Niobocene)" a possible compound?

The so called "Polymerized LiNb (Lithium Niobocene)" is a fictional compound. I heard about this substance being used for an interesting purpose. It reacts to mechanical stress or pressure by ...
At0micCyb0rg's user avatar
0 votes
1 answer
75 views

Modelling planar molecules and their evolutions

I am trying to simulate a chain of molecules which are planar. Can anyone please give me an example of the molecular chain which can stay as planar with it's minimum energy state is planar. A ...
Omar Shehab's user avatar
87 votes
3 answers
5k views

If nothing sticks to Teflon, how does Teflon stick to frying pans?

The most notable characteristic of polytetrafluoroethylene (PTFE, DuPont's Teflon) is that nothing sticks to it. This complete inertness is attributed to the fluorine atoms completely shielding the ...
user avatar
25 votes
5 answers
2k views

Why are smoke odors persistent in fabrics?

Obviously smoke is very complex, but apparently phenol compounds are the main components of wood smoke that produce the characteristic odor. (One of more significant of these compounds seems to be ...
RobertShaw's user avatar
16 votes
1 answer
6k views

Why does gum get harder to chew after a while?

My Sister asked me this: "Why is it that when we chew gum, it is soft and mushy to begin with , but slowly gets firmer and firmer like after 20 mins of chewing?" I think it is because when we ...
The-Ever-Kid's user avatar
14 votes
2 answers
5k views

Why starch (amylose) and cotton (cellulose) are so different?

Both amylose and cellulose have the same "monomer" structure (glucose), so what makes them look/form so differently?
Sparkler's user avatar
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10 votes
1 answer
156 views

How can the solid state structure of cyclopentadienyllithium be explained?

In the solid state, LiCp adopts a polymeric multidecker structure where Li atoms are sandwiched between two Cp rings (shown in this diagram from Organometallics 1997, 16 (17), 3855–3858): If we ...
Deepta Chattapadhyay's user avatar
10 votes
1 answer
683 views

Does the delocalization of p-orbitals ensure conductivity?

For example, polyacetylene is a conjugated system, i.e. with de-localized p-orbitals, but accroding to Chiang et. al. (1977) polyacetylene is semiconducting, and becomes conductive only when doped ...
Sparkler's user avatar
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8 votes
3 answers
7k views

What is the difference between Alkanes and Polymers?

As far as I understand, Polymers are long molecules made of smaller monomers which are Alkenes. But polymers don't have double bonds, so they are saturated. What is the difference between Alkanes and ...
Melkor's user avatar
  • 201
8 votes
2 answers
5k views

How many molecules are there typically in items made of plastics?

In objects made of plastic (and other polymers), how many molecules would one generally expect to find? Intuitively, it seems like, say, a plastic shopping bag or PET bottle couldn't be a single ...
Williham Totland's user avatar
8 votes
1 answer
19k views

Does melting HDPE plastic produce toxic fumes? (melting, not burning)

● The question isn't about burning HDPE but melting it at the proper temperature. (At 120 to 180°C depending on it's density, it becomes gooey. According to the source below the "extrusion" ...
JinSnow's user avatar
  • 439
7 votes
4 answers
1k views

How does the presence of chlorine atoms in PVC make it flame resistant?

In a paper that I'm reading, it states that: The presence of chlorine atoms in polyvinyl chloride make it flame resistant and I'm just wondering why the presence of chlorine atoms will make it ...
QCD_IS_GOOD's user avatar
  • 1,128
7 votes
2 answers
5k views

What makes something biodegradable?

Learning about biodegradable polymers and non-biodegradable polymers. What exactly sets them apart though? Here's the formula from wikipedia for the biodegradable PHB: and here for polypropylene, it'...
QCD_IS_GOOD's user avatar
  • 1,128
7 votes
1 answer
10k views

A thermoset or a thermoplastic?

How do you know if a polymer is a thermoset or a thermoplastic? For example: hydroxybutanoic acid 2-amino-3- hydroxybutanoic acid (I am not sure if these are correct in English) I know what ...
kamal's user avatar
  • 193
6 votes
2 answers
239 views

What would you call the polymerised sheet-like polymer arising from Fittig reaction of 1,3,5-trichlorobenzene?

If we dip a sample of chloroalkane in an ethereal solution, radicals form at the sites where chlorines are attached, which subsequently pair with other radicals. Now, consider 1,3,5-trichlorobenzene: ...
Pritt says Reinstate Monica's user avatar
6 votes
1 answer
13k views

What are the units of 85000 Molecular Weight of a polymer

I have a PVA bottle, which says that the molecular weight (Mw) of PVA is between 85000 - 124000. I know that this means that there are repeated chains of the PVA monomer, but what are the units to ...
user5139637's user avatar
5 votes
1 answer
2k views

Are there chiral carbons in PVC polymers?

PVC polymers are formed from the monomer CH2=CHCl. Below picture is a section of PVC molecule. Is there any chiral carbon centre in this polymer molecule. If yes, then how? I have a source of CAIE ...
Amar30657's user avatar
  • 301
5 votes
1 answer
9k views

Is teflon a poison if ingested? [closed]

Nowadays, a lot of frying pans are made with a non-stick coating. That's usually teflon, or chemically speaking polytetrafluorethylene - $\ce{(C2F4)}_n$. Can you be poisoned if some of that teflon ...
Adinex's user avatar
  • 376
5 votes
1 answer
147 views

Polycyclic nitrogen network?

So today I suddenly stricken with this structure and started to wonder if this polymeric structure of nitrogen is possible or not? If possible then what's its stability?
G.O Ved's user avatar
  • 69
4 votes
0 answers
103 views

How to align povidone-iodine molecules in order to look for optical polarization

In this answer I mention how early polarizing filters (e.g. sunglasses) were made by doping a polymer with iodine atoms and then stretching the film to orient the polymer molecules. Electrons donated ...
uhoh's user avatar
  • 5,888
4 votes
4 answers
3k views

Is graphene a polymer?

A polymer is sometimes defined as a macromolecule with MW larger than 1000 g/mol. So can graphene be considered a polymer?
Sparkler's user avatar
  • 4,275
4 votes
0 answers
669 views

What are the dangers of melting HDPE and silicone? Is it even possible?

I've searched the internet and couldn't find a specific answer. There doesn't seem to be a single recycling company that takes empty silicone tubes (also know as mastic tubes) and recycles them. As a ...
Khalid's user avatar
  • 49
4 votes
0 answers
110 views

How to estimate the mobility constant and the surface energy parameter in the Cahn-Hilliard equation?

As a mathematician, I want to simulate phase separations with the Cahn-Hilliard equation $$ \frac{\partial c}{\partial t} = M \Delta \bigg(\frac{\partial \mu}{\partial c} - \kappa \Delta c \bigg), $$ ...
Henning's user avatar
  • 193
4 votes
2 answers
142 views

Could polydiazene exist?

I am a bit new to the world of chemistry, and after messing around on ChemSpider, I had a thought. Could a polymer like this exist: Due to VSEPR, it would be shaped pretty weirdly and N-N single ...
shan's user avatar
  • 43
4 votes
1 answer
1k views

Why doesn't the oxidation of cellulose oxidise all the alcohol groups, and how does it cause discolouration?

In cellulose, there are several alcohol groups - the two on the ring being secondary alcohols, and the one on the branch being a primary alcohol. I would expect all of these to be oxidised in the ...
Noah P's user avatar
  • 165
3 votes
0 answers
67 views

C60 Fullerene Polymers?

Upon scouring Wikipedia for info about fullerenes to research, I came across this paragraph in the page on Buckminsterfullerene (C60): Under high pressure and temperature, repeated [2+2] ...
mpprogram6771's user avatar
3 votes
2 answers
533 views

Interaction between energy and entropy in highly elastic polymers?

Consider the interaction of energy and entropy in the highly elastic materials of an ideal polymeric network. Now Gibb's free energy cannot be used directly $\Delta H = \Delta G + T \Delta S$ where $\...
Léo Léopold Hertz 준영's user avatar
2 votes
1 answer
131 views

Degree of polymerization with structure-based polymer naming

Polymers may be named using either a structure-based or a source-based nomenclature, as detailed in the IUPAC Purple Book.[1] Therefore, the polymer descibed by $\require{enclose}\ce{\enclose{...
Snijderfrey's user avatar
2 votes
2 answers
3k views

PMMA cross-link temperature

I premise, I’m a physicist and I’m working on a transfer procedure for graphene via CVD, which involves the use of PMMA as a resist layer. Studying this polymer, I still haven’t found what is the ...
MattiaBenini's user avatar
2 votes
1 answer
4k views

Ethyl alcohols use on polycarbonate and acrylics

I have an interesting question about the use of ethyl alcohol on polycarbonate windshields. I have had friends asking me about the use of Pledge Multi-Surface cleaner on their windshields. Some ...
JerShar's user avatar
  • 21
1 vote
1 answer
146 views

Is there an experimental way of measuring the critical concentration of pigment in paint?

With an assigned, generally paint-based, experimental project I've been looking up CPVC or critical pigment volume concentration in binders. CPVC defines the point of addition of pigments after which ...
Spellcaster's user avatar
1 vote
0 answers
30 views

Does polyamide react with hydrocarbons (group III engine oil) in its thermoplastic state?

I need to form (bend) thermoplastic polyamide hose in rubber jacket to a desired shape. I can use heat gun but I thought for better results I could use heated to 150C group III engine oil (your ...
Yoda's user avatar
  • 139
1 vote
1 answer
193 views

Understanding Cahn-Hilliard Equation in terms of Units

The Cahn-Hilliard equation may be formulated as $$ \frac{\partial c}{\partial t} = M \nabla^2 \left(\frac{\partial \hat f}{\partial c}\right), $$ where $c : \Omega \to [0,100]$ describes the ...
Henning's user avatar
  • 193
1 vote
0 answers
2k views

Removing polyimide coating without damaging carbon nor fused silica optical fiber

While being manufactured, an optical fiber (fused silica, 125 microns diameter) has been coated with a carbon coating (~50 microns thick) and an external, ~60 microns thick, polyimide coating. The ...
Andrestand's user avatar
0 votes
0 answers
60 views

How can the torsional barrier of a polymer determined by molecular dynamics?

First consider a simple polymer, like polyacetylene: Its torsional barrier can be determined by DFT calculations by considering "enough" units and performing a simple dihedral scan. "Enough" appears ...
Raphaël's user avatar
  • 1,618
0 votes
0 answers
65 views

pH responsive polymer which is immiscible in water?

Can anyone suggest a pH-responsive polymer, which is immiscible in water (polar solvent) but miscible in oil (e.g vegetable oil)? I want to study the change in the density of such polymers when they ...
Anshuman Sinha's user avatar